For relatively small exhaust turbochargers for use in an internal combustion engine for vehicles, etc., adopted is the configuration in which exhaust gas from the engine fills a scroll formed in a turbine housing, and passes through a plurality of nozzle vanes provided on an inner peripheral side of the scroll to act on a turbine rotor provided on an inner peripheral side of the plurality of nozzle vanes.
Further, a variable displacement turbocharger equipped with a variable nozzle mechanism which is configured to vary an angle of a plurality of nozzle vanes is often used. Examples of this are described in Patent Document 1 and Patent Document 2, for instance.
In this type of variable displacement turbocharger equipped with the variable nozzle mechanism, the variable nozzle mechanism is assembled and then the nozzle mechanism assembly is assembled to the bearing housing or the turbine housing.
When assembling the nozzle mechanism to the bearing, it is necessary to connect a drive ring constituting the variable nozzle mechanism to a link mechanism for converting a drive force of reciprocal displacement from an actuator provided outside the turbine housing or the bearing housing into rotational displacement.
A connection part is configured, as illustrated in FIG. 9, such that a support shaft 01 of the link mechanism penetrating a wall part of the bearing housing to be supported, a lever 03 provided at a tip portion of the support shaft 01 on the housing inner section side, a connection pin 05 provided at an end of the lever 03 and projecting in a direction perpendicular to the lever 03. This connection pin 05 is fittingly inserted in an engagement protrusion 09 formed by cutting and raising a side surface of a drive ring 07 toward the connection pin 05 side to be fitted therein, the drive ring 07 constituting the variable mechanism 06, so as to assemble the variable nozzle mechanism assembly to the bearing housing. As a result, the drive force of reciprocal displacement from the actuator is converted into the rotational drive force of the support shaft 01 by the link mechanism to rotate the whole drive ring 07 through engagement between the connection pin 05 and the engagement protrusion 09.
A front view of this variable nozzle mechanism 06 is illustrated in FIG. 10. The engagement protrusion 09 where the connection pin 05 is inserted is formed in an outer peripheral side of the side surface of the drive ring 07. The variable nozzle mechanism 06 is configured such that a nozzle mount 010, a lever plate 012, the drive ring 07, etc. are assembled together to form the variable nozzle mechanism assembly.
This type of structure where the variable nozzle mechanism is assembled to the housing by engaging the pin part on the lever side with a engagement recess or hole on the drive ring side is described in Patent Document 1 (JP 2008-215083 A) and Patent Document 2 (JP 2009-150363 A).
Described in FIG. 1 and the like of Patent Document 1 is the configuration where reciprocal displacement from an actuator is transmitted to a drive ring 3 via a link 15 and a pin 14.
Further, described in FIG. 7 and the like of Patent Document 2 is the configuration wherein a link 15 is connected to an actuator providing a drive power for nozzle vanes 2, a crank pin 10s is connected to the link 15, and the crank pin 10s engages with a drive ring 3 to rotate the drive ring 3.